Regulating device using copper oxide rectifiers



April 13, 1937. B. E. OHAGAN 2,076,962

REGULATINGDEVICE USING COPPER OXIDE RECTIFIERS Original Filed Oct. 14, 1930 0122223 M Resistance INVENTOR BeznardE. OHagdn. ZLLM HIS ATTORNEY Patented Apr. 13, 1937 Bernard E. lliagan, Swiesvale, li o asslgnor The Union dwitch Signal (Company, vale, Pa, a corporation oi Pennsylvania Original application llilarch 31, M33, Serial No. 663,759, which in turn is a division of? serial No.

488,574, @otoher 1d,

19%, new liatent 1,966,558, dated July it, 19%. Divided and this application November iii, 1935, serial No. ,Ei53

3 i'ilelrns.

My invention relates to regulating devices using copper oxide rectifiers.

One object of my invention is the provision of novel and improved means for regulating the output voltage of a generator.

I will describe two forms of apparatus can bodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. l is a curve showing certain electrical characteristics of a copper oxide rectifier. Figs. 2 and 3 are views showing two forms of apparatus embodying my invention.

Similar reference characters refer to similar parts in each of the views.

The present application is a division of my application Serial No. 663,759. filed March 31, 1933, for Regulating devices using copper oxide rectifiers, which latter case is a division of my application Serial No. 488,574, filed October it, 1930, for Regulating devices using copper oxide rectifiers, which has matured into Patent No. 1,966,558, issued July 17, 1934.

Referring first to Fig. l, the curve shown in 2 this view illustrat s the voltage-resistance char acteristic of the copper oxide rectifier described and claimed in United States Letters Patent No. 1,640,335, granted to L. O. Grondahl on August 23, 1927. -'lhis curve shows that as the voltage across the rectifier increases, the resistance in the low resistance direction decreases, and that the decrease of resistance is much more rapid at low voltages than at high voltages.

Referring to Fig. 2, the reference character G represents a direct current shunt wound generator comprising an armature i and a field 2 controlled by a variable resistance Con neoted in parallel with the shunt field 2, through wires 32 and 32 is arectifler til which permits current to fiow only in the direction indicated by the arrow. Generator G is loaded across the armature and the load circuit is from wire l6, through wire 46, load, wire 4?, and wire is.

When generator G is driven at a constant speed. .the voltage at the terminals of the generator will remain constant, but if the speed of the generator is increased, due to an increase of speed of the driving unit, the terminal voltage will increase. When the voltage of generator G increases, the resistance of the rectifier will decrease, and this decrease of the rectifier resistance causes it to take more current. The increased current taken by the rectifier produces additional voltage drop 55 across a variable resistance 36, thus lowering the ((DH. B ill-229) voltage across, and, consequently, the current through, field winding 2. Ihis weakening of the field strength counteracts any tendency for the output voltage of the generator to increase due to any cause such as an increase in the speed of the driving unit.

Fig. 8 shows how rectifier it may be applied to keep the terminal voltage of an alternating current generator constant when the generator field is energized by current from. an exciter driven by the alternating current generator shaft. Generator G comprises an armature l and a field 2 which is controlled by variable resistance 3%. Connected in parallel with the generator field 2 is a rectifier iii and a differential field 52 which is controlled by variable resistance 3?. The current generated hyexciter E flows from wire it, through wire 56, field 2, variable resistance wire E i, and wire it, and parallel with the field path through variable resistance 3?, dif ferential field 52, wire it, rectifier it, and wire til When the generator speed is increased, due to an increase of speed of the driving unit, the voltage across terminals t9 and Eli is increased and the speed of enciter E is increased, increasing the voltage across armature 48 and across rectifier iii. The resistance of rectifier it decreases causing an increase of current through diiierential field which opposes field 2, and the field intensity of armature i is decreased. The voltage across terminals 39 and 50 therefore remains constant. By connecting rectifier it directly across field 2, as in Fig. 2, the differential field E2 of Fig. 3 can be eliminated.

The main feature of my invention is that since 1 a copper oxide rectifier has the electrical acteristic of lowering its resistance substazand instantaneously when the voltage across increased by a relatively small amount, the r 1 tier may he used eiiectively as a regulating device in. the manner described.

Qne advantage resulting from the use of the copper oxide rectifier in the manner described is that, because of the greater resistance change for a given voltage change obtainable with the rectifier as compared with the resistance change of the usual ballast lamp or negative temperature coefiicient resistor, more sensitive and positive voltage regulation may be had. Another advantags is that since the copper oxide rectifier is practically instantaneous in its response to voltage changes, as contrasted with devices in. which a resistance change follows upon a temperature change requiring an appreciable time interval, the

generator voltage can be maintained within very close limits.

It will be apparent that my invention is not limited to the use of the copper oxide rectifier.

5 as any other suitable resistor having'a negative resistance-voltage coefiicient and the property oi changing its'resistance instantaneously with voltage changes will provide the useful result to which my invention is directed.

10- Although I have herein shown and described only three forms of apparatus-embodying my invention, it is understood. that various changes and modifications may" be made therein'within the scope-oi' theappanded claims without depart- 15 ing from the spirit and scope of my invention.

Having thus described my invention, what! claim is:

i. In combination, an electric generator comprising an armature and a field winding connected in parallel, and a copper oxide rectifier connected in parallel with said field winding ior shunting current from said field winding.

, 2. In combination, an electric generator comprising an armature and a field winding connected in parallel through a series resistor. and a copper oxide rectifier connected across the terminals of said winding for shunting current from said field winding.

3. In combination, an electric generator comprising an armature and a shunt field, a first resistor connected in series with said field, and a second resistor having a relatively high negative resistance-voltage characteristic as well as the prop rty of instantaneously varying its resistance in accordance with voltage changes, said second resistor being connected in parallel with said field for regulating the voltage oi said armature.

BERNARD E. O'HAGAN. 

